Part V, small underground wastewater disposal systems, of the code of waste disposal regulations, adopted by the state division of health and state committee on water pollution in May 1965, as revised by action of the board on June 2, 1967, and June 21, 1967, and issued and published as a code in book form, three (3) copies of which have been filed for use and examination by the public in the office of the city, is hereby adopted by the city as the small underground wastewater disposal systems code within the city, except as it may be altered or modified by the provisions of this section or section 8-3-1 of this chapter. Occupancies in existing buildings may be continued as provided in section 104(g) of the uniform building code, except as to those structures which are found to be substandard as defined in the housing code. (1989 Code § 12-520)